The effect of activating ligands on the intrinsic fluorescence of guanine nucleotide-binding regulatory proteins - PubMed (original) (raw)

. 1987 Jan 15;262(2):752-6.

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The effect of activating ligands on the intrinsic fluorescence of guanine nucleotide-binding regulatory proteins

T Higashijima et al. J Biol Chem. 1987.

Free article

Abstract

The intensity of the tryptophan fluorescence of the alpha subunits of guanine nucleotide-binding regulatory proteins increases when they bind guanosine 5'-O-(3-thio)triphosphate (GTY gamma S). The kinetics of the fluorescence enhancement and of the measured binding of [35S]GTP gamma S are well correlated. The addition of Mg2+ to the nucleotide-bound proteins causes a further, rapid increase in the fluorescence intensity. Similar effects result from exposure of the proteins to F- and Mg2+, and the required concentration of F- is reduced by the inclusion of Al3+. It is presumed that the more highly fluorescent state of the G protein alpha subunits represents their active conformation.

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